77 lines
2.7 KiB
YAML
77 lines
2.7 KiB
YAML
# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
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%YAML 1.2
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---
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$id: http://devicetree.org/schemas/input/touchscreen/ti,am3359-tsc.yaml#
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$schema: http://devicetree.org/meta-schemas/core.yaml#
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title: TI AM3359 Touchscreen controller
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maintainers:
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- Miquel Raynal <miquel.raynal@bootlin.com>
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properties:
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compatible:
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const: ti,am3359-tsc
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ti,wires:
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description: Wires refer to application modes i.e. 4/5/8 wire touchscreen
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support on the platform.
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$ref: /schemas/types.yaml#/definitions/uint32
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enum: [4, 5, 8]
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ti,x-plate-resistance:
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description: X plate resistance
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$ref: /schemas/types.yaml#/definitions/uint32
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ti,coordinate-readouts:
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description: The sequencer supports a total of 16 programmable steps. Each
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step is used to read a single coordinate. A single readout is enough but
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multiple reads can increase the quality. A value of 5 means, 5 reads for
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X, 5 for Y and 2 for Z (always). This utilises 12 of the 16 software steps
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available. The remaining 4 can be used by the ADC.
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$ref: /schemas/types.yaml#/definitions/uint32
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minimum: 1
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maximum: 6
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ti,wire-config:
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description: Different boards could have a different order for connecting
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wires on touchscreen. We need to provide an 8-bit number where the
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first four bits represent the analog lines and the next 4 bits represent
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positive/negative terminal on that input line. Notations to represent the
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input lines and terminals respectively are as follows, AIN0 = 0, AIN1 = 1
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and so on until AIN7 = 7. XP = 0, XN = 1, YP = 2, YN = 3.
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$ref: /schemas/types.yaml#/definitions/uint32-array
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minItems: 4
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maxItems: 8
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ti,charge-delay:
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description: Length of touch screen charge delay step in terms of ADC clock
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cycles. Charge delay value should be large in order to avoid false pen-up
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events. This value effects the overall sampling speed, hence need to be
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kept as low as possible, while avoiding false pen-up event. Start from a
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lower value, say 0x400, and increase value until false pen-up events are
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avoided. The pen-up detection happens immediately after the charge step,
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so this does in fact function as a hardware knob for adjusting the amount
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of "settling time".
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$ref: /schemas/types.yaml#/definitions/uint32
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required:
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- compatible
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- ti,wires
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- ti,x-plate-resistance
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- ti,coordinate-readouts
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- ti,wire-config
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additionalProperties: false
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examples:
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- |
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tsc {
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compatible = "ti,am3359-tsc";
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ti,wires = <4>;
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ti,x-plate-resistance = <200>;
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ti,coordinate-readouts = <5>;
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ti,wire-config = <0x00 0x11 0x22 0x33>;
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ti,charge-delay = <0x400>;
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};
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